1. Field of the Invention
The present invention relates generally to water heaters or boilers and, more specifically, to water heaters having a vertical tube tank and a combustion chamber for supplying heat to the closed tank interior.
2. Description of the Prior Art
Water heaters and boilers (referred to collectively as water heaters in the discussion which follows) typically have a water heater tank, often of the vertical tube type which utilizes fire tubes located above a combustion chamber. The typical prior art gas, oil or gas/oil fired water heaters featured a non-pressurized, external combustion chamber which was typically located on the bottom exterior of the water heater. Vertical shell or V-shell heat exchangers of the above type are well known in the industry.
Thus, for many years, typical water heater construction has provided for the flow of hot gas through a series of tubes mounted in vertical fashion between top and bottom transverse wall sections or support plates within the water heater tank. The products of combustion from the combustion chamber pass vertically upward through the open interiors of the vertical tubes and out a flue outlet. Water was circulated into and out of a chamber in the prior art devices located between the transverse wall sections. The water contacted and circulated about the exterior of the vertical tubes to effect heat transfer to heat the water.
If the combustion chamber could be mounted on the top of the vertical tube assembly, rather than on the bottom of such devices, the products of combustion could be passed downwardly through the vertical tubes in countercurrent fashion to the water being heated. This arrangement could actually result in increased efficiency, since the cold water typically enters a lower portion of the tank and the hot water typically exits an upper portion of the closed tank. Other problems present in the prior art devices could also be reduced or eliminated. One problem with the bottom combustion chamber arrangement is the production of condensate in the burner and other parts of the apparatus. The formation of condensate tends to cause corrosion and deteriorates the water heater internal components shortening the expected life of the device.
However, various problems have also resulted in designs in which the combustion chamber is located at the top, rather than at the bottom exterior of the device. Water stratification has been a problem with the prior art designs which have featured combustion chambers at the top, rather than at the bottom. Whenever a countercurrent flow arrangement is utilized, colder water tends to sit at the bottom of the closed tank interior with hot water accumulating at the top. Steam also tends to be created at any "head" which might exist between the water level and top of the tank interior. If a temperature differential exists between the combustion chamber bottom wall and the tank top wall, steam creation is an even greater problem. Thus, prior art designs have tended to be complicated in design requiring extra insulation, corrosion protection, heavier duty metal construction, and the like.
A need exists for an improved vertical tube water heater apparatus having the combustion chamber at the top of the apparatus, rather than at the bottom.
A need also exists for such an apparatus which provides improved air movement within the device to prevent condensate from being formed within the internal components of the apparatus.
A need also exists for such a water heater having improved water circulation to prevent water stratification and the creation of steam within the closed tank interior.
A need also exists for an improved burner nozzle for use in the combustion chamber of such devices which is specifically designed for a vertical tube water heater having the combustion chamber on the top of the tube assembly and an induction fan on the bottom of the assembly.
A need also exists for an improved vertical tube water heater apparatus having vertical tube components which increase the overall efficiency of the apparatus in heating water.
A need exists for an improved means for introducing cold water into such an apparatus for contacting the vertical tube bundle therein.
A need exists for an improved turbulator design for use in the vertical tubes within the apparatus.
A need exists for such an apparatus which is simple in design and relatively easy to manufacture.